Rack and pinion device for scales



Mar. 6, 1-923. 1,447,307

y J. HoPKlNsoN RACK AND PINION DEVICE FOR SCALES Filed Feb. 5, 1920 2 sheets-sheet l @Mllllm I il* d Mar. e, 1923. y 154473307 J. HOPKINSON RACK AND PINION DEVICE FOR SCALES Filed Feb. 5, 1920 2, sheets-sheet 2 Patented Mar. 6, 1923.

UNITED STATES 1,447,307 PATENT OFFICE.

JOSEPH HOPKINSON, OF DAYTON, OHIO, ASSIGNOR T0 THE COMPUTING SCALE COMPANY, OF DAYTON, OHIO, 'A

CORPORATION OF OHIO.

RACK AND PINION DEVICE FOR SCALES.

To all whom t may concern.'

Be it known that I, JOSEPH HorKiNsoN, a citizen of the United States, residing at Dayton, in the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Rack and Pinion Devices for Scales, of which the following is a full, clear, and exact description.

This invention relates to improvements in scales of the general type shown in the copending application of L. A. Osgood, Serial No. 105,903. In the application referred to, the scale comprises a main lever suitably fulcrumed and having a depending pendulum and also a draft rod extending to a base lever system and imparting the load to the lever. A counter-balancing pendulum is mounted above the beam and is connected thereto in the usual manner. Upstanding from the beam is a member which carries a rack intermeshing with a pinion and driving a weight indicator in the form of a pointer.

The present invention particularly relates to an improved rack construction and a. supporting and adjusting means therefor. The construction is such that rack and pinion friction is reduced to a minimum, and the adjustment means are of such form that various desired adjustments may be made in the factory.

It is among the objects of the present invention to provide for a multiplicity of adjustments so that in building the scale, conditions which affect the intermeshing of the rack and pinion may be met and overcome without undue difficulty. After the main adjustments are made the rack will properly mesh with the pinion and operate without friction, but should occasion arise for further adjustments when the scale is in service, these may be made by repairmen not having the skill of long-experienced Sealers.

Further objects and advantages will be set forth in the accompanying specification and shown in the drawings in which y Fig. 1 shows in elevation a scale having my improved rack supporting and adjusting means applied thereto.

Fig. 2 shows an enlarged view of the rack and supporting means therefor.

Fig. 3 is a sectional view taken on line 3-3 of Fig. 2.

Fig. 4 is an end view of the parts shown 'of the main beam.

in Fig. 2 looking from the left.

Fig. 5 is an end view of the same parts looking from the right.

Figs. 6, 7 and 8 are views similar to Fig. 2 of modifications.

The scale shown in Fig. 1 comprises a main scale beam 10 fulcrumed at 11 and having a depending pendulum 12 below the pivot and a pendulum 13 above the beam and connected thereto by a suitable connection 14. A pointer 15 is arranged to swing over the usual dial, here shown in dotted lines, and this pointer is mounted in the usual manner upon a journaled arbor carrying a pinion 16. Extending upwardly from the beam is an upstanding arm 17 which adjacent the upper end has a side projecting bracket or extension 1S. 'lhe usual draft rod 19 extends downwardly from the beam and connects with the base lever system,

My `improved rack and supporting and adjusting means therefor will now be described. The bracket 18 is drilled with a vertical hole 20, the center line of which is substantially in line with the fulcrum 11 Passing through this hole is a threaded stud 2l (see Fig. 4) adapted to be clamped to the bracket by nuts 22. The upper end of the stud is forked as shown at 23-24. One forked port-ion is drilled to receive a pair of cap bolts 25. The other forked portion is threaded to receive the ends of said bolts. Intermediate the forks 23-24 is a. bracket 26 (see Fig. 3) which is drilled with holes of greater size than the shank of the cap to permit the cap bolts to pass freely therethrough and to allow the bracket to be adjusted vertically, horizontally or angularly with respect to the forks and the stud. After the desired adjustment is made the bolts are tightened, thereby clamping the bracket securely between the forks. This adjustment will hereafter be termed the radial adjustment.

The u per part of the bracket is horizontally dri led to receive a round rod 27. A suitable set screw 2S is provided to clamp the rod in any desired position with respect to the bracket. Suitably fastened to rod 27 is a vertically disposed member 27a carrying a pin 29 which forms a supporting pivot for a member having fastened thereto an arcuate rack 30. The curvature of this rack is such that the pitch line ot the rack practically coincides with the arcot a circle struck from the ulcrum point ll as a center and tangent to the pitch line oi the pinion 16.

ifi vertical member 3l (see Fig. 3) is slotted and through the slot extends a screw by which the member is iastened to the end o't` bracket Q6. The slot provides for a vertical adjustment ot the member 3l with respect to the bracket. The upper end oit' the vertical member is slotted to receive the arcuate rack 3,() and guide the same, thereby preventing` excessive side play and twisting,` ot the rack and possible binding' when in use. lntegral with the vertical member 81 is a shoulder 32 which is drilled and tapped to receive al threaded tube 33 (see Fig. 2). rlhis tube is provided with a shoulder at its forward end and within the tube is a light coil spring 234i which urges a shouldered plunger 35 Jforwardly in the tube. A suitable plug 36 closes the rear end ot the tube and retains the coil spring in position therein.

The threaded tube is provided with a suitable lock nut 3T :tor retaining the saine in any desired position with respect to the supporting' shoulder' )ortion 32 and the lower end ot the tube is provided with a knurled head to facilitate the turning' ot the same with the lingers after the lock nut is loosened. rli`he tube and its threaded socket is slightly inclined `from the vertical as best shown in Fig. 2. This inclination is such that the plunger acts radially against the curved rear face oit the rack, which 'ace is substantially concentric with the pitch line thereof.

lt has been found in practice that it is extremely diiiicult to obtain true pitch line fontact between the pinion and rack, either on account ot' irregularities in the manufacture of the parts or due to the shitting` of the tulcrum ot the pinion and there is a tendency `tor undue friction or binding to exist when the scale is in use, whereby the scale accuracy is effected.

In assembling` the parts the stud 2l is so secured in with respect to the bracket that 'the rack o() is fairly close to the pinion 16. (lare is also taken to align the rack properly with 'the pinion. Thereafter the cap bolts are loosened and a further iine radial adjustment made so as to closely approximate pitch line contact between the rack and the pinion. The enlarged holes in the lu-acket 26 permit. either the right or left hand side ot the rack to be swungl up so as to uniformly engage the pinion. Preferably a slight play is le'lit between the rack and pinion which play is latertaken up by the vertical tension device which includes parts si. ac and a7.

Set screw 2S is then loosened and the rack shitted back or 'forth until the pinion has turned the pointer to stand over Zero or neutral position. rthis constitutes the zero or neutral adjustment. This same adjustment may be used to tilt the rack, should one side be higher than the other.

rllhe member 31 should be so set that the upper end properly guides ther-ack laterally but does not form a. bearingl itor the lower tace of the rack.

The torelggoino` adjustments havingbeen made, the vertical tension adjustment device is so manipulated that plunger 35 presses into light contact with lower 'tace of the 'free end ot' the rack and holds the same yieldingly into substantial pitch line contact with the pinion. It' it is found that this result is not secured recourse may again be had to the radial adjustn'ient for shitting the position oit the rack pivot. lit it is found that the spring` tension ot spring` Sila-is too great or too light. this may be corrected by shifting the plug` 3G out or in with respect to tube 33. Usually it is found that after the radial adjustment is once properly made, the adjustments to the vertical tension device (includinf; the vertical shifting ot tube and the adjustment ot spring tension ot coil spring;f 34e) will in themselves provide ample correction tor maintaining` tree movingl conditions ot the rack and pinion. The depth of enmeshment may be cont-rolled by shitting tube 33 and any variation from true pitch line action of the rack and pinion will be compensated t'or by the spring' Bel- It is of course desirable that the settings be made so Ias to exert the ininiiuum of tension upon the rack and so that the rocking" ot the same about its pivot be reduced tothe minimum.

Vlhile l have herein described one sequence ot adjustments. it will be understood that the sequence set forth is merely to illustrate the functions of the different adjustments and other sequence may be used if desired.

In certain cases it will be found that the making` of one adjustment affects another in which case it is necessary to cut and try until the adjustments desired so correlate with another that the rack meshes properly.

The construction illustrated in Figz similar to the construction previously explained except that the devices for adjustinn' the vertical tension on the rack are disposed between the rack pivot 29 and the pinion 26.

ln addition. the adjustment Jfor the spring tension ot the spring' 34- consists in a shouldered closure 36 which is disposed at the upper end oi' the threadedL tube.

ln Fig. 4' the rack guide 3l supported bv bracket 26 is omitted and a rack guide Si connected to the dial hub is employed. in place ot the vertical tension device previously used a blade spring 39 is employed which presses the rack lightly into contact with the pinion. This construction does not have the screw adjustment for the vertical tension. Any adjustment to be made is affected by bending the blade spring 39.

In Fig. 8 a similar blade spring,l 4() is employed which bears downwardly upon an extended end of the member which carries the rack.

IVhile I have shown my improvements as applied to an arcuate rack to which they are particularly adapted, a straight rack may be used in which the spring` 3a would necessarily have to move the rack and cause it to assume proper contact Vwith the pinion.

l. In a scale in combination, a scale beam, a driving' pinion, an upstanding arm carried thereby and extending' adjacent said pointer driving pinion, and means associated with said arm ior pivot-ally supporting' an arcuate rack below said pinion and yieldingly enmeshing the same therewith, and means for controlling within predetermined limits the depth of enmeshment of the rack and pinion teeth.

2. In a scale in combina-tion, a scale beam, a driving pinion, an upstanding arm carried thereby and extending?r adjacent said pointer driving' pinion, an arcuate rack and means associated with said arm for pivotally supporting an arcuate rack below said pinion and yielding'ly enmcshing the same therewith, said means having` provisions to control within predetermined limits the depth of enmeshment of the rack and pinion teeth and also to control the pressure between said teeth.

3. In a scale in combination, a scale beam, a driving pinion, an upstanding arm carried thereby and extending' adjacent said driving pinion, an arcuate rack means associated with said arm for pivotally supporting an arcuate rack bel w said pinion, and means for adjusting' the radial position of said rack with respect to said arm, said means being,T adapted to be set to retain the rack pivot in fixed position after proper adjustment is sc cured.

at. In a scale in combination, a scale beam, a driving pinion an upstandingY arm carried thereby and extending adjacent said drivingT pinion, an arcuate rack means associated with said arm for pivotally supporting an arcuate rack below said pinion, and mea-ns for shifting the support for the rack pivot with respect to the arm and for thereafter setting tl e same to retain the rack pivot in fixed relation with respect to said arm.

In a scale in combination with a pointer, driving pinion and an arcuate rack oi? a scale beam having an upstanding arm extending adjacent said pointer driving pinion, means associated with said arm for pivotally supporting,T an arcuate rack below said pinion, means for radially adjusting the pivotal support for said rack, means for laterally shifting the rack to set the pointer driving' pinion to zero position, and means for adjusting the vertical tension upon the rack.

6. In a scale having in combination a driving pinion, an arm connected to a moving, part or' the scale, means for driving the pinion from said arm comprising a supporting' structure, a. rack pivotally supported at one end thereby and having a free end, means for adjustino the position of said pivotal support, and means for supporting the free end of the rack and for adjusting` the position ot' the said end.

7. In a scale having in combination a driving pinion, an arm connected to a moving part of the scale, means for driving the pinion from said arm comprising a supporting structure, a rack pivotally supported at one end thereby and having a tree end, means for adjusting the position of said pivotal support, and means for yieldingly pressing the rack into enmeshment with the pinion and for adjusting the amount of said yielding` pressure.

S. In a scale having' in combination a driving' pinion, an arm connected to a moving part or' the scale, means for driving the pinion from said arm comprising a supporting structure, a raelr'pivotally supported at one end thereby and having a free end, means tor adjusting the position of said pivotal support, means for yieldingly pressing the rack into enmeshment with the pinion and for adjusting the amount of said yielding pressure, means for supporting the free end oit the rack and for adjusting the position of said end, and mea-ns carried by said supporting structure for laterally guidthe free end of the rack.

9. In a scale having' in combination a driv` ing pinion, an arm connected to a moving part of the scale, means for driving the pinion from said arm comprising a supporting structure, a rack pivotally supported at one end thereby and having a free end, means for adjusting the position of said pivotal support, means for jf'ieldingly pressing the rack into enmeslnnent with the pinion and ior adjusting the amount of said yielding pressure, means for supporting the free end of the rack and for adjusting the position ot said end, and means for bodily shifting the rack laterally with respect to the pinion and said arm to obtain a proper zero setting for the scale.

10. In a scale having a drivingr pinion and a rack horizontally disposed below the same and spring pressed into enmeshment there-v with, means for radially adjusting' the rack with respect to its support, means for laterally shifting the rack with respect to its support and to said pinion, said means being' also adapted to permit the twisting of the mok with respect to the pinion.

1l. ln n scale having4 in Combination a driving pinion and an arcuate rack horizontally disposed below the saine and spring pressed into enmeshinent therewith,y and means independent of the spring tension for adjusting said rack with respect to said pinion to cause seid ruck to enniesh therewith with lo substantially pitch line Contact.'

l2. ln a. scale having in Combination i driving' pinion A(ind :i arcuate rnolr horizon- JOSEPH HOPKINSON. 

